Servomotor and pressure responsive valve therefor



April 19, 1949. H. PfKuPlEc 2,467,434

SERVOMOTOR AND. PRESSURE RESPONSIVE VALVE THEREFOR Filed May 10, 1947 r4 2 Sheets-Sheet l I0 58 I 3 Z0 April 19, 1949. H. P. KLlPlEC 2,467,434

SERVOMOTOR AND PRESSURE ,RESPONSIVE VALVE THEREFOR Filed May 10, 1947 2Sheets-Sheet 2 J9 55 if 16 54 a4 45' :5

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Patented Apr. 19, 1949 SERVOMOTOR AND PRESSURE RESPONSIVE VALVE THEREFORHarry P. Kupiec, Paramus, N. J., assignor to Air Associates,Incorporated, Teterboro, N. 3., a

corporation of New Jersey Application May 10, 1947, Serial No. 747,295

This invention relates to a hydraulic pressure control valve formaintaining a predetermined pressure range of the 'fiuld in a hydraulicsystem.

The invention has in view a hydraulic valve for controlling the pressureof the fluid in a hydraulic system for opening and closing gun turrets,bomb bays and the like and for raising and lowering landing gear, wingflaps and the like and for operating sheet stamping presses, punchpresses'and other machine tools.

The invention has for an object the provision of a hydraulic valve whichis automatic in operation and which is adapted to be set for operationat low pressures as well as at relatively high pressures.

The invention has for a further object a hydraulic valve of saidcharacter which is adjustable to obtain the desired pressure range orthe minimum and maximum presures in the system.

The invention has for a further object the provision of a hydraulicvalve which is actuated by fluid pressure in the system for maintainingthe pressure therein by controlling the operation of an electricallydriven pump through an electric switch-actuated by the valve.

More particularly the invention has for an object the provision of ahydraulic valve which automatically actuates an electric switch forthrowing into operation the electric motor of a motor driven pump forbuilding up the pressure in the system when the pressure thereinapproaches a predetermined minimum and for throwing out of operation themotor of said motor driven pump when the pressure in the systemapproaches a predetermined maximum.

In the drawings:

4 Fig. 1 is a longitudinal horizontal sectional view through aservo-motor and a pressure responsive valve therefor constructed inaccordance with the invention and illustrating the same in associationwith an electric switch.

Fig. 2 is a fragmentary transverse sectional view taken approximately online 2-2 of Fig. 1.

Fig. 3 is a similar view taken approximately on line 33 of Fig; 1.

3 Claims. (Cl. 121-38) 2 system showing the arrangement of the valve Illtherein.

. Referring to the drawings by characters of reference, the deviceincludes a servo-motor and valve body ill of any desiredconfigurationand which as illustrated is of rectangular formation inlongitudinal and transverse cross-section and is formed with arectangular recess II in which is secured an electric switch l2 havingconductor ends it and J5 extending through a cover 16 secured to thebody Ill to close the side. of the recess H.

The servo-motor and valve body I is provided. with parallel bores l1 andI8 which open through the side wall thereof oppositeto that formed bythe cover I 6. The bore I1 is progressively reduced to provideconcentric bore portions [9, 20 and 2|, the bore portion 2| beinginnermost and communicating with the rectangular recess II. The bore I8is also progressively reduced to provide concentric bore portions 22,23, 24 and 25, the bore portion 25 being innermostand communicating witha transverse passageway 26 which opens into the inner end of the boreportion 20 and is enlarged at its outer end and opens through the sidewall to form the inlet port 21.

Located within the bore portion 20 of the bore ll for reciprocatorymovement therein is a plunger 30 formed with a reduced inner end 3|which is slidably fitted in the inner bore portion 2|. The plunger 30 isengaged by a coiled expansion spring 32 interposed between the outer endthereof and the inner end of a plug 33, which plug is fitted in theouter bore portion l9 and is secured in position therein by aisnap ring34.

The reduced inner end 3| of the plunger 30 is provided with a reducedhead 35 disposed in engagement with a terminal 36 of the electric switchI2. The expansion spring 32 tensions the plunger 30 against the terminal36 to normally retain the same in closed relation with the fixedterminaland at its opposite end the duct 38 opens into the bore portion24 of the bore l8.

The flow of the fluid through the duct 38 is controlled by areciprocatory valve element 49 guidedly mounted in a centrally aperturedannular element 49 located at the inner end of the bore portion 24 withthe bore 4| of the apertured element disposed in alignment with the axisof the bore l8. The valve element 39 protrudes through the bore 4| ofthe annular element 40 and is formed with an enlarged frusto conicalshaped protruding end 42 which is adapted to seat against and close theinner end of the bore 4|. The valve element 39 is provided with aplurality of fluted annular ribs 43 arranged on the periphery thereofwhich slidably fit the bore 4| so as to permit of the free reciprocatorymovement of the valve element therein and which also permits of q theflow of the fluid through 'the flutes 44 in the bore 4| The annularelement 40 is formed with an annular recess 45 in the periphery thereofand with a duct 46 opening at one end into said recess 45 and at itsopposite end opening into the bore 4|. By this construction hydraulicfluid admitted to the bore 4| by the valve element 39 passes throughtheduct 46 into the recess 45 and from the recess 45 through the duct 38into the chamber at the outer end of the plunger 30 to thereby augmentthe pressure against the outer end of the plunger, it being understoodthat the plunger is reciprocated in the bore portion 20 by thedifferential or pressure on the inner and outer ends thereof.

A ball valve element 41 is seated against the outer end of the valveelement 39 and the same is tensionedfor moving the valve elementinwardly so as to open the inner end of the bore 4| and to close theouter end of said bore by engagement of the ball valve element againstthe outer face of the annular element 49 in covering relation with theouter end of the bore 4|. A coiled expansion spring 49 interposedbetween the enlarged inner end of an adjusting screw 49 and aflangedelement 59 tensions the ball valve element "against the valveelement 39. The ball valve element41 engages in a conical depression inthe outer end of the valve element 99 and in a conical depression 52 intheinner face of the flanged element 50. The flanged element 59protrudes through the innermost convolutions of the expansion spring 49and the adjusting screw 49 is threadedly engaged in the outer end of ascrew cap 53 for varying the tension of the expansion spring 48 so as toestablish the desired predetermined pressure at which the plunger 30will be moved inwardly to actuate the electric switch l2. The screw cap53 is threadedly secured in the bore I8 so as to close the outer endthereof and the same is formed with a cylindrical bore 54 openingthrough the inner end thereof in which is arranged the enlarged innerend of the adjusting screw 49 and the expansion spring 48. A look nut 55threadedly engaged on the outer end of the adjusting screw 49 is adaptedto be tightened against the outer faceof the screw cap 53 for lockingthe adjusting screw in set position. The valve element 39 is tensionedby a coiled expansion spring 56 interposed between the frusto-conicalend 42 thereof and the wall of the passageway 26 for resilientlyretaining the valve element 39 in engagement against the ball valveelement 41.

As illustrated in Figs. 1 and 4 of the drawings, the valve element 99 isshown in open relation with the inner end of the bore 4| to therebypermit of the flow of the fluid in the system into the bore 4| andthence through the duct 49, re-

cess 45, duct 48 and into the chamber in the bore portion 20 betwen theplunger 49 and the plug 33 so as to move the plunger inwardly andmaintain the terminal 36 of the switch I2 in closed relation. Theconductors l4 and I5 of the switch |2 are connected in circuit with anelectric motor M of a motor driven pump? which is connected in thehydraulic system S for suplying the fluid pressure in said system. Whenthe switch I2 is thus moved to closed relation the motor M is placed inoperation to drive the pump P.

In order to prevent too frequent opening and closing of the inlet andoutlet ends of the bore 4| preferably a differential in pressure isprovided at which the valve element 99 is moved to open the inlet endand close the outlet end of the duct 4| and to open the outlet end andclose the inlet end thereof. This differential between the cuttingin.and cutting out of the valve element 39 is obtained by the relativeareas of the inlet and outlet ends of the bore 4|. bore 4| is of slighttapered formation with the inlet end which is closed by thefrusto-conical end 42 of the valve element 39 being of slightly largerarea than the outlet end which is closed by the ball valve element 41.The annular element 40 may be provided with any desired size of bore 4|to produce the desired differential. The valve is adapted to operate atrelatively low pressure and at high pressures ranging from 1,300 to3,000 lbs. per square inch in the system depending upon the particularuse or apparatus to be operated by the pressure in the system. For apredetermined pressure of 2,000 lbs. per square inch in the system, thespring 48 would be set so that when the pressure in the system reachesthe set predetermined pressure the valve element 39 would be movedoutwardly to close the inlet end of the duct 4| to thereby effect themovement of the switch l2 to open relation. At

. such predetermined pressure, the duct 4| would be tapered to provide areduced opening at theouter end so that when the pressure in the systemhas dropped to approximately 1,900 lbs. per square inch or adifferential of 100 lbs., the ball valve element 41 would be moved bythe spring 48 to close the outlet end of the duct 4| so as to admitfluid to the inlet end of said duct to thereby effect a closing of theswitch l2. By this construction the motor driven pump is in operationfor a period of time to build up the pressure in the system from 1,900lbs. per square inch to 2,000 lbs. per square inch and is then out ofoperation until the pressure in the system has dropped again to 1,900lbs. per square inch.

When the pump is out of operation the ball valve element 41 is in 'openrelation with the outlet end of the duct 4| to permit of the dischargeof the fluid through the outlet port 51 to the reservoir R.

The pressure at which the valve element 39 cuts out the operation of thepump is the maximum pressure in the system while the pressure at whichthe valve element cuts in" to effect operation of the pump is theminimum pressure in the system. The maximum pressure is established bythe tension set on the spring 48 while the minimum pressure is obtainedby the outlet end of the bore 4| being relatively smaller incross-sectional area than the inlet end thereof.

The plunger 30, plug 44, screw cap 53 and the annular element 40 areeach formed with peripheral recesses in which any desired type ofpacking 58 is arranged for preventing leakage ofthe fluid past theperipheries of said members. It will be seen that the screw cap 53 istightened against an annulus 59 interposed between the inner end thereofand the an-.

nular element =40 for retaining said annular element in position at theinner end of the bore portion 24. The screw cap 53 is formed withopenings 60 through the side wall thereof for permitting of thedischarge therethrcugh of the fluid to the piping leading to thereservoir R.

What is claimed is:

1. In a servo-motor and a pressure responsive device to control itsoperation, a servo-motor and valve body having a pressure chamber, areciprocatory plunger arranged in said chamber and tensioned formovement in one direction, an inlet port communicating with said chamberat one side of the plunger for admitting fluid under pressure againstsaid plunger for moving' the same in the opposite direction, a secondchamber in said body, an outlet port in communication with said lastmentioned chamber, a passageway in said body having inlet andoutlet'openings at its opposite ends in communication respectively withthe inlet and outlet ports,-

fluid from the inlet port through said duct and into said first namedchamber against said plunger for effecting movement thereof, a ballvalve element seated against said reciprocatory valve element and springmeans in said second named chamber tensioning said ball valve elementand said reciprocatory valve element against the pressure of the fluidin the inlet port, and the pressure of said spring and thecrosssectional areas of said inlet and outlet openings in saidpassageway establishing the pressure in the inlet port at which thereciprocatory valve element is moved to close the inlet opening intosaid passageway and the pressure in the inlet port at which the ballvalve element is moved to close the outlet opening of said passageway.

2. In a servo-motor and a pressure responsive device to control itsoperation, a servo-motor and valve body having a pressure chamber, areciproment in 'said' passageway for controlling the inlet openingthereof and the flow of the fluid from the named chamber against saidplunger for efiecting movement thereof, a ball valve element seatedagainst said reciprocatory valve element and adapted to close the outletport of said passageway, and spring means in said second named chambertensioning said ball valve element and said reciprocatory valve elementagainst the pressure of the fluid in the inlet port, and the tension ofsaid spring and the cross-sectional areas of said inlet and outletopenings in said passageway establishing the pressure of the fluid inthe inlet port at which the reciprocatory valve element is moved toclose the inlet opening into said passageway and the pressure of thefluid in the inlet port at which the ball valve element is moved toclose the outlet opening of said passageway.

3. In a servo-motor and a pressure responsive device to control itsoperation, a servo-motor and valve body having a pressure chamber, areciprocatory plunger arranged in said chamber and tensioned formovement in one direction, an inlet port communicating with said chamberatone side of the plunger for admitting fluid under pressure againstsaid plunger for moving the same in the opposite direction, a secondchamber in said body, an outlet port in communication with said lastmentioned chamber, a passageway in said body having inlet and outletopenings of relatively different cross-sectional areas in communicationrespectively with the inlet and outlet ports, said body having a ductopening into said first named chamber at the other side of the 'plu'ngerand opening at its opposite end into said passageway, valve elements forrespectively closing said inlet and outlet openings for controlling theflow of the fluid' from the inlet port through other valve element ismoved to close the outlet catory plunger arranged in said chamber andtensioned for movement in one direction, an inlet port communicatingwith said chamber at one side of the plunger for admitting fluid underpressure against said plunger for moving the same in the oppositedirection, a second chamber in said body, an outlet port incommunication with said last mentioned chamber, a passageway in saidbody having inlet and outlet openings of relatively differentcross-sectional areas in communication respectively with the inlet andoutlet ports, said body having a duct opening into said first namedchamber at the other side of the plunger and opening at its opposite endinto said passageway,

opening of said passageway.

HARRY P. KUPIEC.

REFERENCES CITED The following references are of record in the file ofthis patent:

a valve element mounted for reciprocatory move- UNITED STATES PATENTSNumber Name Date 627,903 Cash, June 27, 1899 1,138,278 Castle May 4,1915 1,175,089 Turner Mar..14, 1916 1,529,434 Hynes Mar. 10, 1925FOREIGN PATENTS Number Country Date 685,216 France Mar. 31, 1931

